1. Field of the Invention
The present invention relates to switching power supply circuits, load driving devices, and liquid crystal display devices.
2. Description of Related Art
Conventionally, as power supply means in a variety of applications, switching power supply circuits (for example, step-up switching power supply circuit, which produce an output voltage by stepping up an input voltage) are widely and commonly used. Methods for controlling switching power supply circuits include current mode control, which involves feedback control in accordance with both the output voltage and the coil current.
Examples of prior art related to what is mentioned above are seen in, for example, Japanese Patent Applications published as Nos. 2010-220355 and 2015-166870.
Inconveniently, however, switching power supply circuits adopting current mode control suffer variation of slope compensation ratio and of PWM (pulse width modulation) gain that accompanies variation of load.
On the other hand, conventional switching power supply circuits of a step-up type leave room for further improvement in line regulation characteristics and line step characteristics (line transient characteristics).